1. Field of the Invention
This invention relates generally to metallic containers and more specifically to lightweight metallic containers that are formed by the drawing and ironing process so as to have a substantially cylindrical vertically upstanding sidewall and an integral base that defines a standing ring.
2. Description of the Related Technology
Conventional metallic cans that are manufactured using the drawing and ironing process are typically fabricated from aluminum, although other metals such as steel could alternatively be used. Aluminum possesses ductility characteristics and can easily be drawn into a cylindrical configuration and ironed to a comparably thin wall thickness.
One popular conventional base design for such metallic cans is characterized by a domed end wall having a downwardly oriented peripheral flange that defines a standing ring on which the can may be supported on an underlying horizontal surface.
The packaging industry is very competitive, and the ability to reduce material costs through lightweighting is extremely important. Accordingly, there is considerable competition within the industry to design metallic can configurations that possess the necessary performance characteristics while using an absolute minimum of material. However, the thinner that the domed end wall of the container is manufactured the more likely it is to buckle outwardly under elevated pressures, such as the pressures that may be encountered during the pasteurization and subsequent handling of carbonated beverages such as beer.
Typically, the downwardly extending standing ring flanges of conventional aluminum can designs were characterized by a relatively constant radius in the area that defined the standing ring. While such designs provided adequate performance characteristics at certain wall thicknesses, there is a continuing desire in the industry to reduce those wall thicknesses in order to save material costs.
A need accordingly existed in the industry for an improved base design for metallic containers that provides enhanced resistance against buckling and other deformation as well as the minimization of material costs.